Android自定义标尺滑动选择值效果

<declare-styleable name="RulerView">    <attr name="textColor" format="color" />    <attr name="textSize" format="dimension" />    <attr name="lineColor" format="color" />    <attr name="lineSpaceWidth" format="dimension" />    <attr name="lineWidth" format="dimension" />    <attr name="lineMaxHeight" format="dimension" />    <attr name="lineMidHeight" format="dimension" />    <attr name="lineMinHeight" format="dimension" />    <attr name="textMarginTop" format="dimension" />    <attr name="alphaEnable" format="boolean" />    <attr name="minValue" format="float"/>    <attr name="maxValue" format="float"/>    <attr name="selectorValue" format="float"/>    <attr name="perValue" format="float"/></declare-styleable>

import android.content.Context;import android.content.res.TypedArray;import android.graphics.Canvas;import android.graphics.Color;import android.graphics.Paint;import android.util.AttributeSet;import android.view.MotionEvent;import android.view.VelocityTracker;import android.view.View;import android.view.ViewConfiguration;import android.widget.Scroller;public class RulerView extends View {  private int mMinVelocity;  private Scroller mScroller; //Scroller是一个专门用于处理滚动效果的工具类  用mScroller记录/计算View滚动的位置，再重写View的computeScroll()，完成实际的滚动  private VelocityTracker mVelocityTracker; //主要用跟踪触摸屏事件（flinging事件和其他gestures手势事件）的速率。  private int mWidth;  private int mHeight;  private float mSelectorValue = 50.0f; // 未选择时 默认的值 滑动后表示当前中间指针正在指着的值  private float mMaxValue = 200;    // 最大数值  private float mMinValue = 100.0f;   //最小的数值  private float mPerValue = 1;     //最小单位 如 1:表示 每2条刻度差为1.  0.1:表示 每2条刻度差为0.1  // 在demo中 身高mPerValue为1 体重mPerValue 为0.1  private float mLineSpaceWidth = 5;  // 尺子刻度2条线之间的距离  private float mLineWidth = 4;     // 尺子刻度的宽度  private float mLineMaxHeight = 420;  // 尺子刻度分为3中不同的高度。 mLineMaxHeight表示最长的那根(也就是 10的倍数时的高度)  private float mLineMidHeight = 30;  // mLineMidHeight 表示中间的高度(也就是 5 15 25 等时的高度)  private float mLineMinHeight = 17;  // mLineMinHeight 表示最短的那个高度(也就是 1 2 3 4 等时的高度)  private float mTextMarginTop = 10;  //o  private float mTextSize = 30;     //尺子刻度下方数字 textsize  private boolean mAlphaEnable = false; // 尺子 最左边 最后边是否需要透明 (透明效果更好点)  private float mTextHeight;      //尺子刻度下方数字 的高度  private Paint mTextPaint;       // 尺子刻度下方数字( 也就是每隔10个出现的数值) paint  private Paint mLinePaint;       // 尺子刻度 paint  private int mTotalLine;        //共有多少条 刻度  private int mMaxOffset;        //所有刻度 共有多长  private float mOffset;        // 默认状态下，mSelectorValue所在的位置 位于尺子总刻度的位置  private int mLastX, mMove;  private OnValueChangeListener mListener; // 滑动后数值回调  private int mLineColor = Color.GRAY;  //刻度的颜色  private int mTextColor = Color.BLACK;  //文字的颜色  public RulerView(Context context) {    this(context, null);  }  public RulerView(Context context, AttributeSet attrs) {    this(context, attrs, 0);  }  public RulerView(Context context, AttributeSet attrs, int defStyleAttr) {    super(context, attrs, defStyleAttr);    init(context, attrs);  }  protected void init(Context context, AttributeSet attrs) {    mScroller = new Scroller(context);    this.mLineSpaceWidth = myfloat(25.0F);    this.mLineWidth = myfloat(2.0F);    this.mLineMaxHeight = myfloat(100.0F);    this.mLineMidHeight = myfloat(60.0F);    this.mLineMinHeight = myfloat(40.0F);    this.mTextHeight = myfloat(40.0F);    final TypedArray typedArray = context.obtainStyledAttributes(attrs,        R.styleable.RulerView);    mAlphaEnable = typedArray.getBoolean(R.styleable.RulerView_alphaEnable, mAlphaEnable);    mLineSpaceWidth = typedArray.getDimension(R.styleable.RulerView_lineSpaceWidth, mLineSpaceWidth);    mLineWidth = typedArray.getDimension(R.styleable.RulerView_lineWidth, mLineWidth);    mLineMaxHeight = typedArray.getDimension(R.styleable.RulerView_lineMaxHeight, mLineMaxHeight);    mLineMidHeight = typedArray.getDimension(R.styleable.RulerView_lineMidHeight, mLineMidHeight);    mLineMinHeight = typedArray.getDimension(R.styleable.RulerView_lineMinHeight, mLineMinHeight);    mLineColor = typedArray.getColor(R.styleable.RulerView_lineColor, mLineColor);    mTextSize = typedArray.getDimension(R.styleable.RulerView_textSize, mTextSize);    mTextColor = typedArray.getColor(R.styleable.RulerView_textColor, mTextColor);    mTextMarginTop = typedArray.getDimension(R.styleable.RulerView_textMarginTop, mTextMarginTop);    mSelectorValue = typedArray.getFloat(R.styleable.RulerView_selectorValue, 0.0f);    mMinValue = typedArray.getFloat(R.styleable.RulerView_minValue, 0.0f);    mMaxValue = typedArray.getFloat(R.styleable.RulerView_maxValue, 100.0f);    mPerValue = typedArray.getFloat(R.styleable.RulerView_perValue, 0.1f);    mMinVelocity = ViewConfiguration.get(getContext()).getScaledMinimumFlingVelocity();    mTextPaint = new Paint(Paint.ANTI_ALIAS_FLAG);    mTextPaint.setTextSize(mTextSize);    mTextPaint.setColor(mTextColor);    mTextHeight = getFontHeight(mTextPaint);    mLinePaint = new Paint(Paint.ANTI_ALIAS_FLAG);    mLinePaint.setStrokeWidth(mLineWidth);    mLinePaint.setColor(mLineColor);    // setValue(1990, 1940, 2016, 1);  }  public static int myfloat(float paramFloat) {    return (int) (0.5F + paramFloat * 1.0f);  }  private float getFontHeight(Paint paint) {    Paint.FontMetrics fm = paint.getFontMetrics();    return fm.descent - fm.ascent;  }  /**   * @param selectorValue 未选择时 默认的值 滑动后表示当前中间指针正在指着的值   * @param minValue   最大数值   * @param maxValue   最小的数值   * @param per      最小单位 如 1:表示 每2条刻度差为1.  0.1:表示 每2条刻度差为0.1 在demo中 身高mPerValue为1 体重mPerValue 为0.1   */  public void setValue(float selectorValue, float minValue, float maxValue, float per) {    this.mSelectorValue = selectorValue;    this.mMaxValue = maxValue;    this.mMinValue = minValue;    this.mPerValue = (int) (per * 10.0f);    this.mTotalLine = ((int) ((mMaxValue * 10 - mMinValue * 10) / mPerValue)) + 1;    mMaxOffset = (int) (-(mTotalLine - 1) * mLineSpaceWidth);    mOffset = (mMinValue - mSelectorValue) / mPerValue * mLineSpaceWidth * 10;    invalidate();    setVisibility(VISIBLE);  }  public void setOnValueChangeListener(OnValueChangeListener listener) {    mListener = listener;  }  @Override  protected void onSizeChanged(int w, int h, int oldw, int oldh) {    super.onSizeChanged(w, h, oldw, oldh);    if (w > 0 && h > 0) {      mWidth = w;      mHeight = h;    }  }  @Override  protected void onDraw(Canvas canvas) {    super.onDraw(canvas);    float left, height;    String value;    int alpha = 0;    float scale;    int srcPointX = mWidth / 2;    for (int i = 0; i < mTotalLine; i++) {      left = srcPointX + mOffset + i * mLineSpaceWidth;      if (left < 0 || left > mWidth) {        continue; // 先画默认值在正中间，左右各一半的view。 多余部分暂时不画(也就是从默认值在中间，画旁边左右的刻度线)      }      /*文字*/      if (i % 10 == 0) {        value = String.valueOf((int) (mMinValue + i * mPerValue / 10));        if (mAlphaEnable) {          mTextPaint.setAlpha(alpha);        }        canvas.drawText(value, left - mTextPaint.measureText(value) / 2,            mTextHeight, mTextPaint);  // 在为整数时,画 数值      }      /*线条*/      if (i % 10 == 0) {        height = mLineMinHeight;      } else if (i % 5 == 0) {        height = mLineMidHeight;      } else {        height = mLineMaxHeight;      }      if (mAlphaEnable) {        scale = 1 - Math.abs(left - srcPointX) / srcPointX;        alpha = (int) (255 * scale * scale);        mLinePaint.setAlpha(alpha);      }      canvas.drawLine(left, mLineMaxHeight + mTextMarginTop + mTextHeight, left, height, mLinePaint);    }  }  @Override  public boolean onTouchEvent(MotionEvent event) {    int action = event.getAction();    int xPosition = (int) event.getX();    if (mVelocityTracker == null) {      mVelocityTracker = VelocityTracker.obtain();    }    mVelocityTracker.addMovement(event);    switch (action) {      case MotionEvent.ACTION_DOWN:        mScroller.forceFinished(true);        mLastX = xPosition;        mMove = 0;        break;      case MotionEvent.ACTION_MOVE:        mMove = (mLastX - xPosition);        changeMoveAndValue();        break;      case MotionEvent.ACTION_UP:      case MotionEvent.ACTION_CANCEL:        countMoveEnd();        countVelocityTracker();        return false;      default:        break;    }    mLastX = xPosition;    return true;  }  private void countVelocityTracker() {    mVelocityTracker.computeCurrentVelocity(1000); //初始化速率的单位    float xVelocity = mVelocityTracker.getXVelocity(); //当前的速度    if (Math.abs(xVelocity) > mMinVelocity) {      mScroller.fling(0, 0, (int) xVelocity, 0, Integer.MIN_VALUE, Integer.MAX_VALUE, 0, 0);    }  }  /**   * 滑动结束后，若是指针在2条刻度之间时，改变mOffset 让指针正好在刻度上。   */  private void countMoveEnd() {    mOffset -= mMove;    if (mOffset <= mMaxOffset) {      mOffset = mMaxOffset;    } else if (mOffset >= 0) {      mOffset = 0;    }    mLastX = 0;    mMove = 0;    mSelectorValue = mMinValue + Math.round(Math.abs(mOffset) * 1.0f / mLineSpaceWidth) * mPerValue / 10.0f;    mOffset = (mMinValue - mSelectorValue) * 10.0f / mPerValue * mLineSpaceWidth;    notifyValueChange();    postInvalidate();  }  /**   * 滑动后的操作   */  private void changeMoveAndValue() {    mOffset -= mMove;    if (mOffset <= mMaxOffset) {      mOffset = mMaxOffset;      mMove = 0;      mScroller.forceFinished(true);    } else if (mOffset >= 0) {      mOffset = 0;      mMove = 0;      mScroller.forceFinished(true);    }    mSelectorValue = mMinValue + Math.round(Math.abs(mOffset) * 1.0f / mLineSpaceWidth) * mPerValue / 10.0f;    notifyValueChange();    postInvalidate();  }  private void notifyValueChange() {    if (null != mListener) {      mListener.onValueChange(mSelectorValue);    }  }  /**   * 滑动后的回调   */  public interface OnValueChangeListener {    void onValueChange(float value);  }  @Override  public void computeScroll() {    super.computeScroll();    if (mScroller.computeScrollOffset()) {   //mScroller.computeScrollOffset()返回 true表示滑动还没有结束      if (mScroller.getCurrX() == mScroller.getFinalX()) {        countMoveEnd();      } else {        int xPosition = mScroller.getCurrX();        mMove = (mLastX - xPosition);        changeMoveAndValue();        mLastX = xPosition;      }    }  }}

<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"  xmlns:app="http://schemas.android.com/apk/res-auto"  android:layout_width="match_parent"  android:layout_height="match_parent"  android:orientation="vertical">  <LinearLayout    android:layout_width="fill_parent"    android:layout_height="fill_parent"    android:gravity="center_horizontal"    android:orientation="vertical"    android:visibility="visible">    <TextView      android:layout_width="wrap_content"      android:layout_height="wrap_content"      android:includeFontPadding="false"      android:maxHeight="17.0sp"      android:text="身高(cm)"      android:textColor="#cc222222"      android:textSize="15.0sp" />    <TextView      android:id="@+id/tv_info_height_value"      android:layout_width="wrap_content"      android:layout_height="wrap_content"      android:layout_marginTop="11.0dip"      android:includeFontPadding="false"      android:maxHeight="24.0sp"      android:textColor="#cc222222"      android:textSize="24.0sp" />    <RelativeLayout      android:layout_width="fill_parent"      android:layout_height="wrap_content">      <com.demo.ruleview.RulerView        android:id="@+id/ruler_height"        android:layout_width="fill_parent"        android:layout_height="68.0dip"        android:layout_marginTop="24.0dip"        app:alphaEnable="true"        app:lineColor="@color/gray"        app:lineMaxHeight="40dp"        app:lineMidHeight="30dp"        app:lineMinHeight="20dp"        app:lineSpaceWidth="10dp"        app:lineWidth="2dip"        app:maxValue="250.0"        app:minValue="80.0"        app:perValue="1"        app:textColor="@color/black" />      <ImageView        android:layout_width="14.0dip"        android:layout_height="46.0dip"        android:layout_centerHorizontal="true"        android:layout_marginTop="40.0dip"        android:scaleType="fitXY"        android:src="@drawable/info_ruler" />    </RelativeLayout>    <Button      android:id="@+id/click"      android:layout_width="match_parent"      android:layout_height="wrap_content"      android:layout_marginTop="10dp"      android:text="点击改变" />  </LinearLayout></LinearLayout>

public class MainActivity extends AppCompatActivity {  private int maxValue = 250;  private int minValue = 80;  private RulerView rulerHeight;  private TextView tvHeightValue;  @Override  protected void onCreate(Bundle savedInstanceState) {    super.onCreate(savedInstanceState);    setContentView(R.layout.activity_main);    rulerHeight = (RulerView) findViewById(R.id.ruler_height);    tvHeightValue = (TextView) findViewById(R.id.tv_info_height_value);    showNumInt();    findViewById(R.id.click).setOnClickListener(new View.OnClickListener() {      @Override      public void onClick(View view) {        showNumInt();      }    });    rulerHeight.setOnValueChangeListener(new RulerView.OnValueChangeListener() {      @Override      public void onValueChange(float value) {        tvHeightValue.setText(String.valueOf(value));      }    });  }  private void showNumInt() {    Random rand = new Random();    int value = rand.nextInt(maxValue - minValue + 1) + minValue;    rulerHeight.setValue(value, minValue, maxValue, 1);    tvHeightValue.setText(String.valueOf(Integer.valueOf(value)));  }}